2002 7.3 Powerstroke
#11
08-27-2017 | 03:44 PM
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F
Depending on the current AM /ambient temps outside, the truck should still start (or sound like its trying) if temps are mild although may require some extended cranking without glow assist.
The glow plugs/control are activated by the key, but the active glow ON times are subject to engine oil temps, BARO, so even if the 'wait to start' is out, the plugs may remain hot. 131*+ and they won't activate.
Usually you'll see the 'load' of the glow plugs or draw indicated on the trucks cluster charge gauge. When the plugs are switched off, the rate of charge will jump up...
My .02 on a manual/switched glow control is not a good idea. If left ON it would add more stress/heat to the UVC (under valve cover) harness's as well as shorten the glow plugs service life. As well as the glow relay. The glow plugs are protected from charge system/batteryover voltage, if a switch is used, that protection is gone..
Fuse #64-30 amp needs to test good (checked with a light or meter, not just visibly) as it supplies voltage into the ignition, then when the key is in Run/Start voltage inputs into the PCM power relay (also check fuse 22-20amp) which in turn supplies voltage into the injector driver module.
The PCM is in control of the 'ground' on the glow relay. Ignition is switched on power/voltage as you noted, but if you add power into the PCM connection on the glow relay you create the potential to damage it.
The 'Ign' connection on the glow relay is actually a input feed off of the PCM power relay (fuse #22 is circuit protection if the glow relay shorts) which like mentioned, gets its power from the ignition/#64..
If you can do some pin point checks with a test light, it may help in a direction to go, or prove out some power distribution points..
If the glow system is deactivated ( if the glows are active it can flame out of the Intake) it should start on a 'short shot' of ether.. Ether is tough on the engine, NOT to be used in concentrate or often, but may help to rule out fail possibilities..
The glow plugs/control are activated by the key, but the active glow ON times are subject to engine oil temps, BARO, so even if the 'wait to start' is out, the plugs may remain hot. 131*+ and they won't activate.
Usually you'll see the 'load' of the glow plugs or draw indicated on the trucks cluster charge gauge. When the plugs are switched off, the rate of charge will jump up...
My .02 on a manual/switched glow control is not a good idea. If left ON it would add more stress/heat to the UVC (under valve cover) harness's as well as shorten the glow plugs service life. As well as the glow relay. The glow plugs are protected from charge system/batteryover voltage, if a switch is used, that protection is gone..
Fuse #64-30 amp needs to test good (checked with a light or meter, not just visibly) as it supplies voltage into the ignition, then when the key is in Run/Start voltage inputs into the PCM power relay (also check fuse 22-20amp) which in turn supplies voltage into the injector driver module.
The PCM is in control of the 'ground' on the glow relay. Ignition is switched on power/voltage as you noted, but if you add power into the PCM connection on the glow relay you create the potential to damage it.
The 'Ign' connection on the glow relay is actually a input feed off of the PCM power relay (fuse #22 is circuit protection if the glow relay shorts) which like mentioned, gets its power from the ignition/#64..
If you can do some pin point checks with a test light, it may help in a direction to go, or prove out some power distribution points..
If the glow system is deactivated ( if the glows are active it can flame out of the Intake) it should start on a 'short shot' of ether.. Ether is tough on the engine, NOT to be used in concentrate or often, but may help to rule out fail possibilities..
#12
08-27-2017 | 04:01 PM
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The 'rattling' relays may be a flag if it's still present. (?)
When you mention 'relay' it's a bit confusing if your talking about glow control, starter solenoid/relay or CJB units.
If you had a voltage drop at the CJB it would most likely affect most all that it protects.
The 7.3 needs 500lbs 'minimum' of high pressure oil during cranking on a start, if not, the injector Driver Module won't fire the injectors.
It also needs a minimum of 150 RPM during cranking. Slower, and it won't start.
A bleeding ICP certainly a wise fix, but may/may not be cause.
Cracked 'fill cups'?
When you mention 'relay' it's a bit confusing if your talking about glow control, starter solenoid/relay or CJB units.
If you had a voltage drop at the CJB it would most likely affect most all that it protects.
The 7.3 needs 500lbs 'minimum' of high pressure oil during cranking on a start, if not, the injector Driver Module won't fire the injectors.
It also needs a minimum of 150 RPM during cranking. Slower, and it won't start.
A bleeding ICP certainly a wise fix, but may/may not be cause.
Cracked 'fill cups'?
#13
08-27-2017 | 04:04 PM
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Welcome to the site..
Generally when the relays chatter like that it's a system low voltage indication.
As a start point, check fuse 64 in the CJB. S/B Battery voltage Y/N ?.
64 feeds the ignition switch for its input power distribution, when in Run/Start the ignition switch then inputs power into the PCM power relay,, which when it closes its contacts is the switched input power distribution for the injector Driver Module. If the voltage is low on 64, batts are known hot,, could be the connector on the CJB or a least part on the checks before moving forward-CJB although would affect the CJB globally..
If the glow relay shorted it may have blown #22 in the CJB
Load-glow distribution for the glow relay output shares voltage for the alt harness/cable,
Generally when the relays chatter like that it's a system low voltage indication.
As a start point, check fuse 64 in the CJB. S/B Battery voltage Y/N ?.
64 feeds the ignition switch for its input power distribution, when in Run/Start the ignition switch then inputs power into the PCM power relay,, which when it closes its contacts is the switched input power distribution for the injector Driver Module. If the voltage is low on 64, batts are known hot,, could be the connector on the CJB or a least part on the checks before moving forward-CJB although would affect the CJB globally..
If the glow relay shorted it may have blown #22 in the CJB
Load-glow distribution for the glow relay output shares voltage for the alt harness/cable,
#14
08-27-2017 | 04:34 PM
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I'm trying to keep up with all the advice as I navigate this site. As it stands I scroll through the entire post looking for new responses. Sorry if I failed 2 respond. I can't find #64 In the manual but found #22 (engine control) and it was blown. I'm learning all of this as I go so please bare w me. Thx guys
#15
08-27-2017 | 08:17 PM
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Posts: 7,489
#64 on my cursor pointer
The fuel pump relay gets its switched power from the PCM power relay as well. Important that 64 is checked with a light or meter.
Also, if the PCM power diode goes bad, same results, not going to be able to feed power distribution to fuel relay-fuel pump, injector driver module, glow relay
The fuel pump relay gets its switched power from the PCM power relay as well. Important that 64 is checked with a light or meter.
Also, if the PCM power diode goes bad, same results, not going to be able to feed power distribution to fuel relay-fuel pump, injector driver module, glow relay
Last edited by Hayapower; 08-27-2017 at 08:21 PM.
#16
08-27-2017 | 10:56 PM
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#64 on my cursor pointer
The fuel pump relay gets its switched power from the PCM power relay as well. Important that 64 is checked with a light or meter.
Also, if the PCM power diode goes bad, same results, not going to be able to feed power distribution to fuel relay-fuel pump, injector driver module, glow relay
The fuel pump relay gets its switched power from the PCM power relay as well. Important that 64 is checked with a light or meter.
Also, if the PCM power diode goes bad, same results, not going to be able to feed power distribution to fuel relay-fuel pump, injector driver module, glow relay
#17
08-28-2017 | 10:41 AM
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what's weird is on my manual that switch is labeled as 116 ignition. It's one of those elongated fuses with the clear top. The one next to it, 115 which says it's the trailer tow battery charger is blown. I tried taking pics.
#64 on my cursor pointer
The fuel pump relay gets its switched power from the PCM power relay as well. Important that 64 is checked with a light or meter.
Also, if the PCM power diode goes bad, same results, not going to be able to feed power distribution to fuel relay-fuel pump, injector driver module, glow relay
The fuel pump relay gets its switched power from the PCM power relay as well. Important that 64 is checked with a light or meter.
Also, if the PCM power diode goes bad, same results, not going to be able to feed power distribution to fuel relay-fuel pump, injector driver module, glow relay
#18
08-28-2017 | 10:53 AM
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#64 on my cursor pointer
The fuel pump relay gets its switched power from the PCM power relay as well. Important that 64 is checked with a light or meter.
Also, if the PCM power diode goes bad, same results, not going to be able to feed power distribution to fuel relay-fuel pump, injector driver module, glow relay
The fuel pump relay gets its switched power from the PCM power relay as well. Important that 64 is checked with a light or meter.
Also, if the PCM power diode goes bad, same results, not going to be able to feed power distribution to fuel relay-fuel pump, injector driver module, glow relay
#20
08-28-2017 | 11:19 AM
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#64 on my cursor pointer
The fuel pump relay gets its switched power from the PCM power relay as well. Important that 64 is checked with a light or meter.
Also, if the PCM power diode goes bad, same results, not going to be able to feed power distribution to fuel relay-fuel pump, injector driver module, glow relay
The fuel pump relay gets its switched power from the PCM power relay as well. Important that 64 is checked with a light or meter.
Also, if the PCM power diode goes bad, same results, not going to be able to feed power distribution to fuel relay-fuel pump, injector driver module, glow relay